Enhancements to ShadowAccountManager

Adds implementations for:
  getAuthenticatorTypes()
  addOnAccountsUpdatedListener()
Merge pull request #746 from awrichar/account

Enhancements to ShadowAccountManager
Update README to point to version 2.2 :smile:
Javadoc for Robolectric#checkActivities
PackageResourceLoader now knows what an Animator is. Fixes #653
killing space
Merge pull request #751 from coreydowning/load-animator-resources

PackageResourceLoader now knows what an Animator is. Fixes #653
Make ThemeTest actually test stuff.
Merge pull request #752 from coreydowning/fix-theme-test

Make ThemeTest actually test stuff.